1. Field of the Invention
The invention relates to the operation of a mesh-type network, particularly as defined in IEEE standard 802.11s, formed by a plurality of network nodes.
2. Background of the Related Art
It is known that IEEE standard 802.11s for WLAN mesh networks, which is in the process of being developed (see IEEE P802.11s™/D1.01 Draft STANDARD for Information Technology-Telecommunications and information exchange between systems-Local and metropolitan area networks-Specific Requirements-Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) specifications: Amendment: ESS Mesh Networking), uses 6 addresses in the data packets. In this case, as FIG. 1 shows, the 5th and 6th addresses are used to store the MAC addresses of source and destination nodes that are outside the WLAN mesh network.
In this connection, methods were proposed, as in the case of a path calculation in the standard routing protocol of IEEE 802.11s, “Hybrid Wireless Mesh Protocol (HWMP),” which can impart a connection between external nodes, i.e., network nodes that are not mesh nodes and are therefore located outside the mesh network, and the corresponding mesh boundary nodes to which these external nodes are adjacent. However, these methods are only suitable for long-lasting mappings (allocations) between the external nodes and the mesh boundary nodes. In particular, mobility of stations STA that are connected to mesh access points MAP and can switch from one mesh access point to the next, as indicated in FIG. 2 by the mobile station STA at the mesh access points MAP, is supported only inadequately.
The proposed “Radio-aware Optimized Link State Routing (RA-OLSR)” protocol, which is an optional, proactive routing protocol of IEEE standard 802.11s [1, Section 11A.7], uses a proactive mechanism to announce all allocations between stations and mesh access points to all other mesh nodes. Every mesh access point has a local database known as a local association base (LAB), which contains all stations associated with this mesh access point. The content of this local database is periodically sent to all nodes in the mesh network by means of a so-called local association base announcement (LABA) message. Said nodes store the data from the received messages in their so-called global association base (GAB) global data and thereby know to which mesh access point they must forward data packets that are targeted to specific stations.
If a station switches from one mesh access point to another, then, at the latest with the next periodic LABA message, the changes will be announced in the RA-OLSR mesh network. Referring to the depiction in FIG. 2, this means that the LABA message of the old mesh access point of the mobile station no longer contains the address of the mobile station and that the LABA message of the new mesh access point of the mobile station now contains the address of the mobile station.